Steam boiler cleaner and method for cleaning steam boilers



United States Patent C The present invention is directed to a steam boiler cleaner and inhibitor composition and to a method for cleaning steam boilers, and more particularly to a steam boiler cleaner and inhibitor composition which may be directly added to the steam boiler without the necessity for draining and/or blowing off the same, and to a method by WhiChSlJCh cleaning and inhibitor composition may be utilized in connection with steam boilers.

Until the advent of the present invention, there has not been available. a cleaner and inhibitor composition which may be utilized in conjunction with steam boilers without the necessity for taking the steam boiler offstream. Thus, conventionally, steam boilers for apartment houses and industrial installations are cleaned by removing the boiler blow-off plug, fitting piping into ,the boiler, firing the boiler, and adding water repeatedly in sufiicient quantities to allow the surface oil, grease and other surface impurities to run off. Following this surface blow-off, cleaning agents are then added to the boiler water, and the boiler is fired for a number of hours, and then drained and refilled. A corrosion inhibitor then may be added to the boiler water. This procedure normally takes about five hours for small boilers and considerably more for larger boilers, and is a serious matter in connection with units which must be onstrearn for extended periods of time.

This invention has an an object the provision of a steam boiler cleaner and inhibitor composition which may be utilized in steam boilers without the necessity for either blowing-off surface oil, grease and other surface impurities, or draining the steam boiler.

This invention has as still another object the provision of a steam boiler cleaner and inhibitor composition which safeguards a steam boiler against corrosion.

This invention has as still another object a novel process for cleaning a steam boiler,

Other objects will appear hereinafter.

These and other objects are accomplished by the steam boiler cleaner composition of the present invention which consists essentially of about 83 to 93 weight percent of diatomaceous earth, about 4 to 9 weight percent of anhydrous sodium sulphite, and about 1 to 2 /2 weight percent of anti-foaming silicone. Preferably, although not necessarily, about 2 to 4 weight percent of tannic acid should be present in the composition, optimally about 3 weight percent of tannic acid. In particular, a composition consisting of 88 /2 weight percent of diatomaceous earth; 7 weight percent of anhydrous sodium sulphite; 3 weight percent of tannic acid; and 1 /2 weight percent of anti-foam silicone is preferred.

The process of the present invention comprises adding the above-identified composition to the water inventory of a steam boiler while the steam boiler is in operation. Within a period of approximately thirty minutes oil and grease impurities are removed from the surface of the boiler water, and a suspension precipitates or begins to precipitate to the bottom of the boiler, where it is drawn off as sludge.

The preferred diatomaceous earth of the composition of the present invention is the grade designated Filter Cel by the Johns Manville Sales Corporation. This is a finely divided diatomaceous earth. While I do not wish to be bound by any theory of operation of the steam boiler cleaner and inhibitor of my invention, it is my belief that this diatomaceous earth when present in admixture in the 3,294,584 Patented Dec. 27, 1966 composition of my invention and added to the water inventory of an operating steam boiler absorbs. the oil, grease, rust and scale from the boiler water. By a chemical reaction, the nature of which is not explainable by the chemical literature, within a period of approximately thirty minutes, the diatomaceous earth in conjunction with the absorbed oil, grease, rust and scale precipitates, or commerces to precipitate, as a sludge.

The operation of the sodium sulphite is to remove free oxygen from the boiler water. This in conjunction with the tannic acid and the diatomaceous earth minimizes corrosion of the steam boiler due to the removal of oxygen.

The efiicacy and synergistic action of the aforesaid diatomaceous earth, tannic acid, and sodium sulphite is greatly reinforced by the presence of the anti-foam silicone, which is present in an amount suflicient to prevent foaming. The addition of the silicone above about 2 /2 weight percent is largely wasteful of the silicone as no additional anti-foaming action will be achieved. The silicone eliminates bubbling, surging and priming of the water inventory in the steam boiler producing a relatively dry steam which facilitates the cleaning and inhibitin action of the composition of the present invention.

A preferred anti-foam silicone which I have used in the composition of my invention is AF24 sold by the General Electric Company at Waterford, New York. This silicone weighs between 8.3 and 8.4 pounds per gallon, has a specific gravity of 0.995 to 1.006 at 25 C., a viscosity of 500 centipoises maximum at 25 C., a flash point of 460 F., and a pour point of below 30 F. AF24 is dispersible in water.

I have found that approximately grams of the composition of my'invention should be utilized for each 700 feet of boiler rating. For boilers rated in excess of 10,000 feet, approximately 100 grams of my composition should be used per 1000 feet of rating.

The use of the steam boiler cleaner of the present invention in a steam boiler enables the steam boiler to be cleaned without the necessity for taking the boiler off stream, and in particular without the necessity for a time consuming surface blow-olf of surface oil, grease, and other surface impurities and draining and refilling of the boiler.

The boiler cleaner composition of the present invention may be blended by dry powder blending, with the liquid antifoam silicone being mixed with the remaining components which are in the form of solid powders, and in its blended form may be stored indefinitely in metal containers.

Not only does the composition of the present invention achieve cleaning of the steam boiler, but also it effects corrosion inhibition of the metal surfaces which come in contact with the water.

The presence of the composition of the present invention in the operating steam boiler water inventory causes precipitation to commence within about 30 minutes. However, for complete sludge removal, a more extended time period, such as several days, should be allowed. Thus, under normal circumstances, the sludge should be remoyed after several days from the time the composition is added to the boiler.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specificationas indicating the scope of the invention.

I claim:

1. A steam boiler cleaner and inhibitor composition consisting essentially of about 83 to 93 weight percent of diatomaceous earth, about 4 to 9 weight percent of anhydrous sodium sulphite, and about 1 to 2 /2 weight percent of silicone.

2. A steam boiler cleaner and inhibitor composition consisting essentially of about 83 to 93 Weight percent of diatornaceous earth, about 4 t 9 weight percent of anhydrous sodium sulphite, about 2 to 4 weight percent of tannic acid, and about 1 to 2 /2 weight percent of silicone.

3. A steam boiler cleaner and inhibitor composition consisting of 88 /2 weight percent of diatomaceous earth, 7 weight percent of anhydrous sodium sulphite, 3 Weight percent of tannic acid, and 1 /2 weight percent of silicone.

4. A method for cleaning steam boilers which comprises adding a composition consisting essentially of about 83 to 93 weight percent of diatomaceous earth, about 4 to 9 weight percent of anhydrous sodium sulphite, and about 1 to 2 /2 weight percent of silicone to the water inventory of an Operating steam boiler, continuing the boiler operation for a period of at least 30 minutes whereby a sludge including boiler water contaminate is formed, and then removing precipitated sludge from the bottom of the steam boiler.

5. A method for cleaning steam boilers which cornprises adding a composition consisting essentially of about UNITED STATES PATENTS 2,627,502 2/1953 Bird 252- X 2,767,138 10/1956 Loefiler et al 134-7 X 2,968,616 1/1961 Bernard 252-175 X FOREIGN PATENTS 528,210 7/1956 Canada,

MORRIS O. WOLK, Primary Examiner.

JOSEPH SCOVRONEK, F. W. BROWN,

Assistant Examiners. 

4. A METHOD FOR CLEANING STEAM BOILERS WHICH COMPRISES ADDING A COMPOSITION CONSISTING ESENTIALLY OF ABOUT 83 TO 93 WEIGHT PERCENT OF DIATOMACEOUS EARTH, ABOUT 4 TO 9 WEIGHT PERCENT OF ANHYDROUS SODIU, SULPHITE, AND ABOUT 1 TO 2 1/2 WEIGHT PERCENT OF SILICONE TO THE WATER INVENTORY OF AN OPERATING STEAM BOILER, CONTINUING THE BOILER OPERATION FOR A PERIOD OF AT LEAST 30 MINUTES WHEREBY A SLUDGE INCLUDING BOILER WATER CONTAMINATE IS FORMED, AND THEN REMOVING PRECIPITATED SLUDGE FROM THE BOTTOM OF THE STEAM BOILER. 